README.md

Noah

ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. All of these kinds of services are used in some form or another by distributed applications.

Essentially Noah is a port of parts of that functionality into a stateless RESTish application.

Some background

It's probably worth reading the following blog posts before going any further to clear up any possible misunderstandings.
Noah is not a direct replacement for ZK. It's a conceptual port. More than anything, it was an itch I needed to scratch:

Quick Start

Design Goals

The system MUST support RESTful interaction for operations where REST maps properly

The system MUST support basic concepts of hosts, services, applications and configurations

The system MUST support horizontal scaling.

Additionally:

The system SHOULD be flexible in deployment options.

The system SHOULD support watches similar to ZooKeeper

The system SHOULD support pluggable callbacks for watches.

The system SHOULD support being a client of itself.

Opinionated Stack

Noah is somewhat opinionated in its stack. Noah attempts to minimize the external requirements wherever possible to allow for the widest possible installation options.
However, excellent work has been done to create performant and well-tested libraries that would be foolish to ignore. To this end, the current requirements are:

The above stack provides much of the functionality needed to port over ZooKeeper concepts.

Redis

Redis is the backbone of the system. Through the native datatypes and pubsub capabilities, much of the heavy lifting has already been done.

Sinatra

Sinatra is the perfect library for creating API-only style applications. It allows you do focus on the meat of what an endpoint should do instead of the hassle of creating the endpoint.

Ohm

Ohm is quite simply the most unobtrusive and flexible orm for Redis. It gets out of the way and allows you to very easily interact directly with Redis if the need arises

EventMachine

EventMachine combined with Redis pubsub forms the basis of the Watcher and callback system.

Motivation

It's something I've wanted to do for a while. Everytime I've needed something like Zookeeper, Zookeeper has always been too bulky and had too many moving parts. I've also always needed to interact with it from more than just Java or C. Sometimes it's been Ruby and sometimes it's been Python.

In the end, we reinvent the wheel ANYWAY. Maybe we do something like have our CM tool write our application config files with a list of memcached hosts. Maybe we write our own logic around (shudder) RMI to do some chatty broadcasting around the network for finding local nodes of type X. We always reinvent the wheel in some way.